Determine the Direction of Force

When evidence includes the breakage of glass by a bullet, the direction of travel may be easily determined.  Find the sharply tapered pieces nearest to the hole (radial break pieces). Be sure you know which is the inside (or outside!) and look at the glass from the side. 

The force of the bullet hitting one side will break away a crater on the opposite side of the glass.  The glass is tapered, from the impact surface away to a larger hope on the side opposite the impact.  This “rule” is also true for surfaces such as “particle board”, gypsum drywall, plywoods... and large bone structures such as skulls, jaws and hips.

Be careful with larger holes as left by rocks.  The rule is still true, however the pieces remaining around the hole may not always be the right ones to evaluate for “directionality”.

Fracture lines radiate from the break.  Find a piece near the break and examine the area where the lines come closest together. Turn it to look at the edge as shown in the right hand picture above.

Which way was the bullet traveling?

Which surface is still flat and which is cratered? What direction was the force? Remember - the flat side “faces the shooter” and the crater is the “”away”:side of this target.

You are correct if you said the bullet was traveling (as shown above) from top to down..